A composite material member is made of a light metal, and strength and durability in a joined part between constituent materials of the composite material member are improved, and production cost is decreased. The composite material member of the present invention contains a main material composed of a light metal or a light metal alloy which can be molded by casting; and a secondary material composed of a metallic material different from the main material or an inorganic material, the secondary material being joined to the main material by integrally casting with the main material, wherein a porous material is arranged on a part of a boundary area or entire boundary area between the main material and the secondary material.